Internal combustion engine



J. J. M CARTHY INTERNAL COMBUSTION ENGINE Nov. 5, 1940.

Filed Dec. 13, 1958 .42 tor/z ef'ys'.

Patented Nov. 5, 1940 NI ED sTATEs PATENT OFFICE Appl cation-December 13, 1938, Serial N0. 245,387

a Gaims. (01. 123-51) This invention relates to internal combustion engines and more'pa'r'ticularlyto engines of the so-called opposed piston type. I

It is a well known fact that the crank case and the crank shaft bearings of an internal combustion engine of the highly eflicient opposed piston type must be built strong in order to take the stresses of explosion. The main disadvantage therein resides in the large weight per horse 0 power of the engine, whereas the trend is to re-- duce the weight per horse power.

It is the'primary aim and'object of the present invention to provide an internal combustion engine of the opposed piston type which has a small weight per horsepower and can be manufactured at a low cost.

This and other objects of the present inventhe crank shaft bearings may be constructed light in weight. More particularly, one of the pistons is provided with a cup-shaped extension open to the cylinder chamber and of an outside diameter substantially equal to the cylinder diameter, while the other piston has a projecting head piece which enters said cup and forms therein a combustion chamber when the pistons move through preassigned portions of a cycle including their inner dead center positions. Suitable provisions are also made for admitting air into the cylinder, for emitting the products of combustion therefrom and for forcing fuel into the combustion chamber. Before explaining in detail the present inventionit is to be understood that the invention is not limited in its application to the details 40 of constructionand. arrangement of parts illustrated in the accompanying drawing, since the invention is capable of. other embodiments and ofbein'g practiced or carried out in various ways. Also it is to be understoodthat the phraseology In the drawing:

Fig. 1 is a vertical section through a cylinder of an internal combustion engine of the opposed piston type which embodiesthe present invention.

Fig. 1A is a fragmentary sectional view of the or terminology'employed herein is-for the purengine, disclosing more particularly the location of the fuel openings in one of the pistons with respect to the exhaust ports in the cylinder.

Fig. 1B is another fragmentary'secti'onal view of the engine, disclosing a modified arrangement of the exhaust ports in the cylinder.

Fig. .2 is a section similar to Fig. 1, showing the opposed pistons in a different position of their respective cycle, however Referring to the drawing, the reference numeral Hi designates a crank case, having one or more cylindrical bores l2, each to receive a cylinder liner Id. The engine is preferably a multicylinder engine with the cylinders in line, there being only ,onecylinder shown in the drawing because they are cross-sections through the engine. While the cylinders'are formed by steel liners in the illustrated embodiment of the invention, making it possible to make the crank case of alight weight material, such as aluminum or an aluminum alloy. and to reduce the and to omit the cylinder liners, in which case the engine becomes naturally heavier.

Inasmuch as all cylinders of the engine are pistons therein. Slidable on the wall i8 of the cylinder 14 are two opposed pistons i8 and 20 which are drivingly connected in the usual manidentical, only one will be described hereinafter in detail and in connection. with the opposed .8

ner by means of connecting rods 22 and 24, re-

manifolds I! on opposite sides of the cylinder which conduct air under pressure from a super.-;"

charger (not shown) to said intake ports by way of passages 44 which are provided in brackets 46 interposed between said intakemanifolds l2 and the crank case "I. The exhaust ports 40 are in permanent communication with exhaust manifolds which have a common discharge opening at 50. The crank case I0 is suitably cored out to. provide transverse passages 52 and 54 between adjacent cylinders which are in communication with the intake and exhaust ports 38 and Ill, respectively, of adjacent cylinders and provide communication between the intake and exhaust manifolds l2 and 48, respectively, on opposite sides of the crank case. Thus, supercharged air conducted through the intake manifolds 42 has always access to all intake ports 38 of a cylinder, and the productsof combustion may always be discharged throughall-exhaust ports of a cylinder into one of the exhaust manifolds l8 andco'nducted from there to the commondischarge opening 50.

The crank shafts 3| and 32 are connected in 7 any suitable manner to operate in timed relation with each other. This may, for instance, be accomplished by a train of gears (not shown). mounted on an end plate I6 which is preferably integral with the crank case' II. The crank shafts 3|! and 32 are preferably soangularly coordinated that the exhaust ports 40 are uncovered by the piston it before the intake ports 38 are uncovered by the piston 2|, and said exhaust ports are covered by the piston it before said intakeports are covered by the piston 20. The products of combustion may then escape prior to the admission of supercharged air into the cylinder and the admitted air may thoroughly its head 58 with a cup-shaped extension 80 the -rim 62 of which has an outside diameter that is substantially equal to the inside diameter of the cylinder M. The piston 20 is provided with a projecting head piece 64 which enters the cavity 88 in the extension 60 of the other piston l8 in.

the manner shown in Fig. 2 and defines therein a combustion chamber ll when both pistons I8, 20 are substantially in their inner dead center positions. Fuel is injected into the highly com- .pressed air in the combustion chamber 68 at a selected point in each cycle of the pistons 18, 20. The fuel is conducted from fuel nozzles 10 in the cylinder wall into the combustion chamber 68 through openings 12 in the rim 62 of the cupshaped extension 60 of piston l8, said openings aligning with said fuel nozzles when piston I 8 assumes th momentary position shown in Fig. 2' during each cycle. The exhaust ports 40 in the cylinder liner I4 are so arranged that the fuel openings 12 in the piston extension I never communicate with said exhaust ports. This may be readily accomplished by so spacing the two adjacent exhaust ports between which each fuel opening I! of the reciprocating piston passes that neither of said fuel openings ever communicates with said exhaust ports (Fig. 1A). The nozzles ll are in communication with conven: tional fuel pumps 14 which in turn communicate in any suitable manner with a fuel supply (not shown) The fuel pumps II are mounted on the earlier mentioned brackets ll which also provide journal bearings for shafts II, having earns 18 for operating the fuel pumps. The cam shafts 18 are driven -in any suitable manner in timed relation with the crank shafts SI, 32 so that the fuel pumps 14 force fuel through the nozzles 10 when the openings-12in the cup-shaped extensuitable packings sion ll of piston I8 align with said nozzles (Fig.1).

In order to hold an explosive charge of air and fuel comparable in quantity and pressure to a charge in the same cylinder between the. heads of two conventional pistons, the combustion chamber is of a relatively large inside diameter in comparison with the cylinder diameter.

tion in Fig. 2, and the projecting head piece 64.

of piston 20 is preferably likewise conical and has a small clearance from the rim '2 when the Pistons are at or near their inner dead center positions. Thus, no air can possibly be trapped between thehead ll of piston 20 and the adjacent end of the rim '2 on piston l8 and impede the movement of the pistons. Also, theclearance between the conical rim if on piston I 8 and the conical projecting head piece 64 on piston 20 is at iirst considerable when said head piece just enters the cavity 66, wherefore the flow of air into said cavity is not greatly obstructed. However, this clearance becomes smaller and smaller as the projecting head piece I of piston Ill progresses into the cavity 56 in piston l8 until said clearance becomes so small at the time of combustion that the exploded charge cannot effectively reach the cylinder. wall and induce stresses in the same. The projecting head piece 04 of piston 20 should enter the cavity 68 in piston ll a considerable distanc in order to obtain the above conditions, and the cavity 86 must accordingly be of a substantial depth and should preferably be more than one-third of the cylinder diameter. In order that practically all air in the cylinder is at the time of combustion present in the combustion chamber 68 and immediately available for the combustion, the pistons I8, 20 are so coordinated that the head of piston 20 is then in close proximity too the adjacent end of the rim '2 on piston I 8, leaving a negligible air gap therebetween.

The crank case II is also provided with ,a

cored-out water jacket ll which is open at the.

cylinder bores 12 and otherwise closed and continuous throughout the length of the engine from its inlet to its outletv (neither shown). At the cylinder bores 12, the water jacket is closed by the liners M which are fitted intosaid bores in the manner shown in the drawing, there being ll provided in said liners to prevent leakage of cooling water from the jacket 85 The fuelnoszles ll may be so tightly screwed or otherwise fitted into aligned and abutting bosses I of the crank case l0 and each cylinder liner that cooling water in the jacket ll will not leak along the fuel nozzles 1|. 7

Due to the decreasing clearance between the conical side wall of the cavity 88 in piston l8 and the conical periphery of the head piece 04 on piston'zl as said head piece moves into said cavity, air is forced at increased velocity into the combustion chamber ll shortly before the combustion takes place. This secures the important advantage that the air which is forced into the combustion chamber 88 at such in-,

creased velocity intersects the fuel as it lainjected into the combustion chamber through the openings 12 in the rim .2 of piston II and In the disclosed embodiment of the invention. the exhaust ports 40 are below the extension 60 a of the piston I: when the latter is in the position shown in Fig. 1. While the products of combustion in the cavity 86 are satisfactorily ejected through the illustrated exhaust ports 40 due to the difference in pressure in the cylinder chamber and in the exhaust manifolds l8 and due to the scavenging of said cylinder chamber and of said cavity It by the compressed intake air, at least one further exhaust port 400 (Fig. 13) may be provided in the cylinder liner H and crank case III which permanently communicates in any suitable manner with the exhaust manifolds l8 and communicates with a fuel opening 12 in the piston l8 substantially when the latter assumes the outermost position shown in Fig. 1, thereby providing for straight-through scavenging of the cylinder chamber and of the piston cavity 8.

I claim: I 1. In an internal combustion engine, the com blnation of a cylinder having in its wall a fuel duct and axiallyspaced intake and exhaust ports on opposite sides, respectively, of said duct; and two pistons slidable on the cylinder wall and operating in opposite directions in timed relation with each other, one of said pistons having on its head a cup sliding with its rim on the cylinder wall and having in said rim near 40 the cup bottom a hole registering with said fuel duct substantially when said one piston is in its innermost position and registering with an exhaust port when said one piston is'in its outeron its head adapted to enter said cup when said pistons move into their innermost position, said a cup and said boss cooperating to form a combustion chamber, and the pistons. covering the exhaust and intake ports, respectively, except most position, and the other piston having a boss when they are'substantially 'in theiroutermost positions.

2. In aninternal combustion engine, the combination of a cyinder having in its wall afuel duct and axially spaced intake and exhaust ports on opposite sides, respectively, of said duct, one of said exhaust ports being-farther distant from the intake ports than the remaining exhaust ports; and two pistons slidable on the cylinder wall and operating in' opposite directions in timed relation with each other, one of said pistons having on its head a cup sliding with its rim on the cylinder wall and having in said rim near the cup bottom a hole registering with said fuel duct substantiallywhen said one piston is in its innermost position and registering with said one exhaust port' when said one piston 18' in its outermost position, and the other piston having a boss on its head adapted to enter said cup when said pistons move into their innermost position, said cup and said boss cooperate to form a combustion, chamber, and the pistons normally cover the intake and exhaust ports, respectively, and uncover the same except said one exhaust port when' the pistons are substantially inltheir outermost positions.

the adjacent edges of'two successive remaining exhaust ports, and said hole is of such size as to be out of registry with said remaining exhaust ports in any position of said one piston.

JOHN J. MCCAR'I'HY. 

